(i) Field of the Invention
The present invention relates to a lubricant for a refrigerating machine, and more specifically, it relates to a lubricant for a refrigerating machine, which contains a chlorinated polyether having a specific structure and which is excellent in lubricating properties.
(ii) Description of the Prior Art
Examples of FLON refrigerants used in refrigerating machines include CFC (chloro-fluoro-carbon) typified by R11, R12 and R13, HCFC (hydrochloro-fluoro-carbon) typified by R22 and R142b, and HFC (hydrofluoro-carbon) typified by R134a.
It is known that lubricating properties on the sliding portion of the compressor of a refrigerating machine are improved by a FLON refrigerant containing chlorine, particularly by the function of chlorine present in its molecule. However, a FLON such as CFC in which all the hydrogens of the hydrocarbon are replaced with halogen atoms is difficult to decompose in the atmosphere, which leads to the breakage of an ozone layer. For this reason, limitations of production and consumption of CFC are being planned by the International Convention. Therefore, in the place of CFC, refrigerants such as HCF and HFC will be used in the future, but in these refrigerants, the content of chlorine is lower than in CFC, and the improvement effect of the lubricating properties is less than in CFC. In consequence, the lubricant to be used is required to be more excellent in the lubricating properties.
Of the refrigerating machines using the FLON refrigerant, the machines having rotary type compressors, even if being of small size, have a high refrigerating power and a less noise at the time of operation, and so they are widely used in domestic refrigerators, room air conditioners, car air conditioners and the like. With regard to this type of refrigerating machines, however, surface pressure in the sliding portion of the compressor is high and sliding velocity is also high, and therefore with regard to the lubricating properties of the lubricant, requirements are heightened more and more along with the performance enhancement of the compressor.
Heretofore, as the lubricants for refrigerating machines using the FLON refrigerant, there have been used mineral oils such as a naphthene and a paraffin as well as synthetic oils such as an alkylbenzene, a polyglycol and a poly-.alpha.-olefin, but when the base oil is used singly, the lubricating properties are not always sufficient, depending upon conditions to be used.
Thus, in fact, a wear inhibitor such as a phosphate is added to the base oil so as to improve the lubricating properties.